(120a) Toward Monodisperse Single-Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWNTs), which may be conceptualized as sheets of graphene rolled into a cylinder, possess extraordinary optical, thermal, electronic, and mechanical properties. These attributes make SWNTs extremely appealing for materials, nanoelectronic, and biomedical applications. However, as-produced SWNTs come in a wide range of lengths, diameters, and chiralities. Each combination of these dimensions possesses its own unique characteristics. Many applications would greatly benefit from the availability of monodisperse SWNTs; that is, nanotubes of the same geometric proportions. Recent efforts toward monodispersity include the use of ultracentrifugation, a highly scalable technique in which liquid SWNT dispersions are spun at very high accelerations. In a centrifugal field, the minute differences in hydrodynamic properties of the nanotubes are magnified, allowing for separation by both length and diameter. Additionally, separation by chirality or electronic type may be achieved by exploiting selective affinity and packing structure of dispersants. In this work, ultracentrifugation process parameters were explored in an effort to optimize the sorting of nanotubes by diameter, chirality, and electronic type.